# CVE-2026-80205

## Summary

- **CVE ID:** CVE-2026-80205
- **Severity:** HIGH
- **CVSS Score:** 8.7 (CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N)
- **CWE:** CWE-1333
- **Published:** Aug 26, 2026
- **Last Modified:** Sep 1, 2026

## Description

NLTK versions before 3.10.0 contain a regular expression denial of service vulnerability in Text.findall() and TokenSearcher.findall() methods that accept user-supplied regular expressions without validation or timeout. Attackers can supply crafted regex patterns that cause catastrophic backtracking, resulting in indefinite CPU saturation and denial of service to all users of the Python process.

## Affected Products

- nltk — nltk (0)
- nltk — nltk (3.10.0)

## References

- [CNA](https://github.com/nltk/nltk/security/advisories/GHSA-rrv8-h7p8-rx55)
- [CNA](https://www.vulncheck.com/advisories/nltk-before-3.10.0-redos-via-text-findall-unvalidated-regex)
- [CVE](http://www.openwall.com/lists/oss-security/2026/09/01/3)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.49%
- **EPSS Percentile:** 40.6

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-11._